Speed limiters for internal combustion engines with controlled coil ignition

ABSTRACT

The speed limiter comprises, on an element rotated at a speed proportional to that of the engine, a contact fixed with respect to this element and a movable contact adapted to approach the fixed contact under the effect of the centrifugal force and against the effect of a return spring. One of these contacts is connected to the secondary winding of the ignition coil of the engine and the other to ground. When the speed of the engine reaches a predetermined threshold, the movable contact touches the fixed contact and cuts off the ignition of the engine by grounding said secondary winding. A screen of electrically insulating material is guided on said element and connected mechanically to the movable contact so that it is inserted between the two contacts as long as the speed of the engine is less than a limit itself less than said threshold but close to the latter and so that it retracts when this speed exceeds the said limit.

United States Patent Grosseau Dec. 4, 1973 SPEED LIMITERS FOR INTERNAL COMBUSTION ENGINES WITH CONTROLLED COIL IGNITION Inventor: Albert Grosseau, Chaville, France Assignee: Societe Anonyme Automobiles Citroen, Paris, France Filed: Mar. 7, 1972 Appl. No.: 232,536

Foreign Application Priority Data Mar. 16, 1971 France 7109134 US. Cl 200/80, 123/102, 123/146.5 A Int. Cl H0lh 35/10, F02d 31/00 Field of Search 123/102, 118, 198 D,

References Cited UNITED STATES PATENTS 9/1933 Smith 123/118 6/1956 Buchmann 123/118 Primary Examiner-Laurence M. Goodridge AttorneyRichard K. Stevens et a1.

[5 7 ABSTRACT The speed limiter comprises, on an element rotated at a speed proportional to that of the engine, a contact fixed with respect to this element and a movable contact adapted to approach the fixed contact under the effect of the centrifugal force and against the effect of a return spring. One of these contacts is connected to the secondary winding of the ignition coil of the engine and the other to ground. When the speed of the engine reaches a predetermined threshold, the movable contact touches the fixed contact and cuts 1 off the ignition of the engine by grounding said secondary winding. A screen of electrically insulating material is guided on said element and connected mechanically to the movable contact so that it is inserted between the two contacts as long as the speed of the engine is less than a limit itself less than said threshold but close to the latter and so that it retracts when this speed exceeds the said limit.

5 Claims, 4 Drawing Figures SPEED LIMITERS FOR INTERNAL COMBUSTION ENGINES WITH CONTROLLED COIL IGNITION The invention relates to speed limiters, for internal combustion engines with controlled coil ignition, which comprise, on an element (such as the insulating body of the ignition distributor) driven in rotation at a speed proportional to that of the engine, a contact fixed with respect to this element and a movable contact adapted to approach the fixed contact under the action of the centrifugal force and against the action of a return spring, one of these contacts being connected to the secondary winding of the ignition coil of the engine and the other to ground so that, when the speed of the engine reaches a predetermined threshold, the movable contact touches the fixed contact and cuts ofi the ignition of the engine by grounding the abovesaid secondary winding.

These speed limiters are acceptable with new or little worn spark-plugs but when the spark-plugs reach some degree of wear, they cause operational defects in the engine and especially, a drop in the threshold of speed imposed on the engine and jerkiness and irregularities on acceleration.

It is an object of the invention to overcome these operational faults.

To achieve this purpose, the speed limiter according to the invention is characterised by the fact that a screen of an electrically insulating material is guided on the said element and connected mechanically to the movable contact so that it is interposed between the two contacts as long as the speed of the engine is less than a limit itself less than the abovesaid threshold but neighbouring the latter and that it is withdrawn when this speed exceeds the said limit.

In this way, whatever the degree of wear of the sparkplugs, it is ensured, on the one hand, that an arc is not formed between the two contacts whilst the speed of the engine has not reached the limit concerned, since the screen prevents this by increasing the length of the leakage path between the secondary ignition circuit and ground, and, on the other hand, that the electric arc, which is formed on the separation of the contacts, is cut as soon as the speed of the engine drops below this limit.

The invention will, in any case, be well understood with the aid of the supplementary description which follows and of the accompanying drawing, which description and drawing relate particularly to preferred embodiments of the invention given purely by way of illustrative but non-limiting example.

In the drawing:

FIG. 1 shows in diagrammatic axial section a conventional speed limiter and illustrates the drawbacks that the invention seeks to eliminate.

FIGS. 2 and 3 show, respectively in diagrammatic axial section and in partial section along the line IIlIII of FIG. 2, one embodiment of a speed limiter constructed according to the invention.

FIG. 4, lastly, shows similarly to FIG. 2, a second embodiment of a speed limiter constructed according to the invention.

Before entering into the description of the two embodiments, it would appear useful to recall the state of prior art in the technique and the drawbacks that ex-' isted.

As is seen in FIG. 1, the known speed limiter comprises, on the insulating body 1 of the rotary element of the ignition distributor, a contact 2 fixed with respect to the body 1 and a movable contact 3 adapted to approach the fixed contact 2 under the effect of centrifugal force (shown diagrammatically by an arrow F) and against the action of a return spring 4, the movable contact 3 being connected, in the manner shown diagrammatically by the arrow f, to the secondary winding of the ignition coil (not shown) of the engine and the fixed contact 2 to ground. More precisely, the spring 4, which is metallic, connects the movable contact 3 to the distributing finger 5 which cooperates with studs 6 connected respectively to the spark-plugs of the engine and the fixed contact 2 is constituted or borne by one of the ends of a metallic strip 7 of which the other end is in contact with the shaft 8 of the distributor, which shaft is housed in part in a bore 9 of the body 1 and is connected to ground.

When the speed of the engine reaches a threshold which it must not exceed, the centrifugal force F, by overcoming the action of the spring 4, causes the contact 2 to be touched by the contact 3, which grounds the finger 5 and cuts the ignition due to the resulting short-circuit. TI-Ie speeds of the engine diminishes until the contact 3 is separated from the contact 2 and the engine resumes normal operation.

The operational faults of the engine, which have been indicated above, arise from the fact that, when the contact 3 is close to the contact 2, there is produced, in the interval e between the two contacts, a poorly controlled electric arc when the spark-plugs reach some degree of wear.

It is to overcome these defects that the speed limiter according to the invention comprises a screen (FIGS. 2 and 3) or 10b (FIG. 4) which is guided on the insulating body 1a or 111 and connected mechanically to the movable contact 3a or 3b so that it is interposed between the fixed contact 20 or 2b and the movable contact 3a or 3b, as long as the speed of the engine is less than a limit itself less than the abovesaid threshold but in the neighborhood of the latter, and this screen is withdrawn when this speed exceeds the said limit.

In general, reference numerals have been used to denote the elements of FIGS. 2 and 3 and FIG. 4 which are analogous to those of FIG. 1, but supplemented by the letter a for the elements of FIGS. 2 and 3 and the letter b for those of FIG. 4.

In the embodiment of the FIGS. 2 and 3, the movable contact 3a is mounted inside a housing 11 formed in the body 1a, by means of an axle l2 situated so that this contact can pivot, against the action of the return spring 4a, in a plane passing through the axis of the bore 9a and the screen 10a is mounted to be slidable, in guides 13 forming part of the body In, by accompanying the angular movements of the movable contact 3a around its axle 12. The screen 10a and the guides 13 have preferably, as seen in FIG. 2, a profile as an arc of a circle and movable contact 3a possesses a projec tion 14 engaged in a groove 15 provided in the screen 10a. The movable contact 3a is advantageously constituted by a metallic strip comprising a loop traversed by the axle 12, a lug folded to a right angle to form the projection 14, another lug 16 serving as a stop against the bottom of the housing 11 and a folded end 17 intended'to come into contact with the fixed contact 2a.

There is thus obtained an improved speed limiter whose operation is as follows.

When the engine is stopped or rotates at relatively low speed, the elements of the speed limiter occupy the position of the assembly of FIG. 2. The lug 16 of the contact 3a is applied against the bottom of the housing 11 under the effect of the spring 4a, which connects electrically (as in the case of FIG. 1) the finger 5a and the contact 3a. The screen a occupies a high position in which it is interposed between the'contacts 2a and 3a. When the speed increases, the movable contact 3a pivots around the axle 12 (the pivoting movement being shown diagrammatically by a mixed line indicating the path of the end 17) and draws the screen 10a downwardly, by the projection 14, until the abovesaid speed limit having been reached, the screen 10a is no longer between the contact and the end 17 of the contact 3a. At this moment, an arccan be produced between the contact 2a and the end 17 but, contrary to the case of FIG. 1, the gap analogous to e is welldefined and arcing does not depend on the degree of wear of the spark-plugs. The contact 3a pursues its pivoting movement if the speed continues to increase and comes into abutment by its end 17 against the contact 20 which insures its grounding. This causes a reduction in the speed of the engine. The spring 4a brings back the contact 3a (in clockwise direction, in FIG. 2) and the configuration of the parts of the speed limiter is such that the screen 10a is again interposed between the two contacts when the latter are slightly separated.

In the modification shown in FIG. 4, the pivoting contact 3a is replaced by a conductive slider 3b which is guided so as to be slidable radially over the insulating body 1b, against the action of a return spring 4b, and the screen 10b is constituted by the end of an element 18 pivotable around an axle 19 at right angles to the axis of the bore 9b. The slider 3b possesses a ramp 20 which cooperates with a boss 21 of the element 18, a second spring 22 acting on the latter to hold its boss 21 in contact with the ramp 20. TI-Ie fixed contact 2b is here constituted by the end of a rod 7b which is connected to ground, through a metallic spring 23, a ball 24 projecting into the bore 9b and the shaft of the distributor (not shown) engaged in this bore.

The operation of the modification of FIG. 4 is similar to that of the embodiment of FIGS. 2 and 3. By moving radially outwardly as the speed of the engine increases, the slider 3b, by the action of its ramp 20 on the boss 21 of the element 18, causes the latter to rotate in anticlockwise direction in FIG. 4. The screen 10b, which was previously interposed between the end of the slider 3b and the fixed contact 2b, becomes withdrawn from a certain speed limit onward and, finally, the slider 3b comes to touch the contact 2b, which causes the engine to slow down. The screen then resumes its position between the two fixed and movable contacts.

Whilst, in the case of FIGS. 2 and 3, the elastic characteristics of the single spring 4a act to fix the speed limit at which the screen withdraws and the speed threshold of the engine, the characteristics of the two springs 4b and 22 act conjointly in the case of FIG. 4.

As is self-evident, and as emerges already from the foregoing, the invention is in no way limited to those of its types of application, nor to those embodiments of its various parts, which have been more especially indicated; it encompasses, on the contrary, all modifications.

I claim:

1. Speed limiter, for internal combustion engines with controlled coil ignition, for use on a rotary element arranged for rotation at a speed proportional to that of the engine, said speed limiter comprising, in combination, a contact fixed with respect to said rotary element and a movable contact adapted to approach the fixed contact under the effect of the centrifugal force on said rotation and against the effect of a return spring, one of these contacts being connected to the secondary winding of the ignition coil of the engine and the other to ground, said fixed and movable contacts being arranged so that, when the speed of the engine reaches a predetennined threshold, the movable contact touches the fixed contact and cuts off the ignition of the engine by grounding said secondary wind ing, and a screen of electrically insulating material guided on said rotary element and connected mechanically to the movable contact so that it is between the two contacts as long as the speed of the engine is less than a limit itself less than said threshold but close to the latter and so that it is no longer between said two contacts when this speed exceeds the said limit.

2. In an ignition distributor, wherein said rotary element has an insulating body, the combination of a speed limiter according to claim 1, and said rotary element.

3. Speed limiter and rotary element combination according to claim 2, including a housing and guides formed in the insulating body, an axle, in said housing, on which said movable contact is mounted and situated so that the movable contact can pivot therein, against the action of a return spring, in a plane passing through the axis of rotation of the insulating body, the screen being mounted in slideable manner in said guides and thereby accompanying the angular movements of the movable contact around its axle.

4. Speed limiter and rotary element combination according to claim 3, wherein the screen and the guides of the insulating body have a circular arcuate profile and wherein the movable contact has a projection en gaged in a groove provided in the screen.

5. Speed limiter and rotary element combination according to claim 2, wherein the movable contact is constituted by a conductive slider which is guided so as to be slidable radially over the insulating body, a return spring opposing said radial sliding, and wherein the screen is constituted by the end of an element pivotable around an axis at right angles to the axis of rotation of the rotary element, the slider possesses a ramp which cooperates with a boss of the screen element, and a second spring is arranged to act on the screen element to hold said boss in contact with said ramp. 

1. Speed limiTer, for internal combustion engines with controlled coil ignition, for use on a rotary element arranged for rotation at a speed proportional to that of the engine, said speed limiter comprising, in combination, a contact fixed with respect to said rotary element and a movable contact adapted to approach the fixed contact under the effect of the centrifugal force on said rotation and against the effect of a return spring, one of these contacts being connected to the secondary winding of the ignition coil of the engine and the other to ground, said fixed and movable contacts being arranged so that, when the speed of the engine reaches a predetermined threshold, the movable contact touches the fixed contact and cuts off the ignition of the engine by grounding said secondary winding, and a screen of electrically insulating material guided on said rotary element and connected mechanically to the movable contact so that it is between the two contacts as long as the speed of the engine is less than a limit itself less than said threshold but close to the latter and so that it is no longer between said two contacts when this speed exceeds the said limit.
 2. In an ignition distributor, wherein said rotary element has an insulating body, the combination of a speed limiter according to claim 1, and said rotary element.
 3. Speed limiter and rotary element combination according to claim 2, including a housing and guides formed in the insulating body, an axle, in said housing, on which said movable contact is mounted and situated so that the movable contact can pivot therein, against the action of a return spring, in a plane passing through the axis of rotation of the insulating body, the screen being mounted in slideable manner in said guides and thereby accompanying the angular movements of the movable contact around its axle.
 4. Speed limiter and rotary element combination according to claim 3, wherein the screen and the guides of the insulating body have a circular arcuate profile and wherein the movable contact has a projection engaged in a groove provided in the screen.
 5. Speed limiter and rotary element combination according to claim 2, wherein the movable contact is constituted by a conductive slider which is guided so as to be slidable radially over the insulating body, a return spring opposing said radial sliding, and wherein the screen is constituted by the end of an element pivotable around an axis at right angles to the axis of rotation of the rotary element, the slider possesses a ramp which cooperates with a boss of the screen element, and a second spring is arranged to act on the screen element to hold said boss in contact with said ramp. 